Median AQI
29
Good
Puerto Rico · County air quality · 2025
Bayamon County, Puerto Rico
Median AQI 29 (Good). 88.5% of monitored days rated Good, direct from EPA Air Quality System stations.
- 29
- Median AQI
- 88.5%
- Good-air days
- 0
- Unhealthy days
- 72%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Bayamon County's air is good on balance, cleaner than the median US county, a median AQI of 29 with 88.5% of 113 monitored days in the Good band, driven mainly by PM2.5.
- 29
- median AQI · Good
- 88.5%
- days rated Good
- PM2.5
- main pollutant
- 72%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 102.
Data updated July 2026
- Good · 100 d · 88.5%
- Moderate · 11 d · 9.7%
- USG · 2 d · 1.8%
How did Bayamon County's air break down in 2025?
Across 113 monitored days, 100 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 102 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 113 days monitored. Median AQI: 29 (Good).
Insights: Bayamon County, Puerto Rico. EPA monitors recorded a median Air Quality Index of 29 across 113 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 100 (89%) fell in the Good band (AQI 0–50), 11 (10%) registered Moderate readings, and 2 (2%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 54, while the worst single-day peak hit 102 (USG). Residents averaged about 26.5 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (113 days). Across the 2020–2025 trend window, good days shifted by -159 and the median AQI moved +8 points, placing the multi-year trajectory at worsening. The worst single reading over the 2020–2025 window was AQI 102, usg but never Unhealthy. Nearby counties show comparable readings: Caguas (94.3% good, AQI 3); Catano (64.6% good, AQI 44); Fajardo (85.7% good, AQI 29); Guayama (100.0% good, AQI 18); Guaynabo (86.0% good, AQI 30); Mayagnez (96.9% good, AQI 12).
Air Quality Summary
Good Days
88.5%
100 of 113 monitored days
13.5pp vs 75% target
Max AQI Recorded
102
USG
Health Grade
Good
90th-pct AQI 54
Bayamon County, Good days share 88.5%
National avg
Share of monitored days at AQI 0-50 (Good band).
Bayamon County, Unhealthy-or-worse share 0.0%
National avg
Share of monitored days above AQI 150 (Unhealthy or worse). Bar maxes at 10% (worst-county ceiling).
AQI Day Breakdown (2025)
Distribution of 113 monitored days across EPA AQI categories.
Good
100
88%
Moderate
11
10%
USG
2
2%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Bayamon County.
- PM2.5 · 113 days · 100.0%
Health Impact Assessment
Good
Bayamon County's air quality is rated Good based on 88.5% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 88.5% of monitored days in 2025, with a median AQI of 29. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is PM2.5, driving AQI on 113 of 113 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Bayamon County. Best year: 2022 (342 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 259 | 11 | 0 | 0 | 21 | 69 |
| 2021 | 320 | 27 | 0 | 0 | 10 | 77 |
| 2022 | 342 | 16 | 0 | 0 | 15 | 77 |
| 2023 | 193 | 23 | 0 | 0 | 22 | 74 |
| 2024 | 268 | 45 | 1 | 0 | 27 | 124 |
| 2025 | 100 | 11 | 2 | 0 | 29 | 102 |
How does Bayamon County compare?
How Bayamon County compares
Good-day share better than US avg
Bayamon County 88.5%
Caguas County, Puerto Rico 94.3%
US average 76.5%
Median AQI better than US avg
Bayamon County 29
Caguas County, Puerto Rico 3
US average 38
Unhealthy days / yr about average
Bayamon County 0
Caguas County, Puerto Rico 0
US average 0
Other Counties in Puerto Rico
Air quality comparison for nearby counties in Puerto Rico.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Bayamon County.
Fajardo County, Puerto Rico
AQI 29 · 85.7% good
Grant County, Oklahoma
AQI 29 · 90.0% good
Jackson County, Wisconsin
AQI 29 · 76.0% good
Nez Perce County, Idaho
AQI 29 · 84.0% good
Roane County, Tennessee
AQI 29 · 84.1% good
Washington County, Nebraska
AQI 29 · 84.3% good
What Bayamon County's air means for you
The air here stays in the breathable range year-round, with PM2.5 the main thing to watch.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-PM2.5 days, the guide explains what a median of 29 means for exposure. Health guidance
- See how Bayamon County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Bayamon County with its Puerto Rico neighbours before drawing a conclusion about the region. All of Puerto Rico
Based on 113 EPA-monitored days in 2025; figures reflect only days the monitors reported. Source: EPA Air Quality System annual summaries.
More Air Quality Data
Air Quality Guides
Frequently Asked Questions
What is the air quality in Bayamon County, Puerto Rico? ▼
Bayamon County has a median Air Quality Index (AQI) of 29, rated "Good." 88.5% of monitored days (100 out of 113) had good air quality in 2025.
What is the main pollutant in Bayamon County? ▼
The primary pollutant in Bayamon County is Fine Particles (PM2.5), which was the main AQI driver on 113 days (100% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Bayamon County have? ▼
In 2025, Bayamon County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 102.
Is the air quality in Bayamon County getting better or worse? ▼
Air quality in Bayamon County is worsening based on 5-year trends (2020-2025). Best year: 2022 with 342 good days. Worst year: 2025 with 100 good days.
What does AQI 29 mean for health? ▼
Bayamon County's median AQI of 29 falls in the "Good" category. See the <a href="/guides/understanding-aqi" class="underline">AQI category guide</a> for what each range means for health.
How does Bayamon County compare to other counties in Puerto Rico? ▼
Bayamon County has 88.5% good air days. Nearby counties in Puerto Rico: Caguas (94.3% good), Catano (64.6% good), Fajardo (85.7% good), Guayama (100.0% good), Guaynabo (86.0% good), Mayagnez (96.9% good).
What is the 90th percentile AQI in Bayamon County? ▼
The 90th percentile AQI for Bayamon County is 54, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 102 (USG).
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by County dataset, 2020–2025 (aqs.epa.gov). For current conditions (not shown here — this page is historical annual data), see EPA AirNow (airnow.gov). See our methodology for how AQI, median, and coverage figures are computed.
Informational only, not professional advice. Data from EPA AQS. See our disclaimer.
Every figure on PlainAir is rendered directly from EPA AQS air-quality monitoring data, no number is typed in by an editor. This page draws directly on EPA AQS air-quality monitoring data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.